The Internet Group Management Protocol (Internet Group Management Protocol, abbreviated as IGMP) is a host-to-router signaling mechanism used by Internet Protocol (Internet Protocol, abbreviated as IP) multicast in a user network segment, and implements the function of managing group members by interacting IGMP messages between the host and the router. A multicast service is generally implemented based on the IGMP protocol. Specifically, multicast traffic from a multicast source is firstly forwarded between routers; the last-hop router copies the multicast traffic to each access virtual local area network (Virtual Local Area Network, abbreviated as VLAN); and then a switch distributes the multicast traffic on the local area network until the multicast traffic is distributed to a receiving host.
When users access a multicast network by using different VLANs as their identifiers but request a same channel, the last-hop router copies multicast traffic of the same channel to each VLAN, thereby ensuring that each VLAN user can receive the multicast traffic successfully. Using a scenario illustrated in FIG. 1 as an example, multicast requests of users access the multicast network by using VLAN 100 to VLAN 300; when all the users request a same channel, a router R copies the multicast traffic of the channel to VLAN 100 to VLAN 300 respectively to ensure that each user can receive the multicast traffic successfully.
During the implementation of the present invention, the inventors find that the prior art has at least following problems: When users request the same channel, 201 copies of traffic of the same channel with different VLAN tags exist in a link router R→switch SA→switch SB, that is, multiple copies of traffic with different VLAN tags are forwarded on the local area network, which occupies a large amount of bandwidth and causes a huge waste of network bandwidth.